1. Field of the Invention
This intention relates to a medical pump device constituted so as to provide a pulsating blood flow superimposed on a spontaneous blood flow and, more specifically, it relates to a novel medical pump device effective to the improvement for the prognosis of the artery reconstructed by bypassing operation against the occlusion of a peripheral artery such as a limb artery. This invention further relates to a method for compensating a deviation of a measured blood flow rate in an artery from a referenced blood flow rate to thereby bring the measured blood flow rate near to the referenced blood flow rate.
2. Discussion of Background
In recent years, arterial obliteration (obliterans) has come into a problem as one of adult diseases with the increase in arteriosclerosis due to various causes. As the therapeutical method for the arterial obliteration, a so-called bypassing operation that recovers the blood flow by bypassing the portion of the occluded blood vessel with a patient's vein or an artificial blood vessel made of polytetrafluoroethylene or the like became popular along with the development and popularization of blood vessel surgery.
The bypassing technology provides satisfactory results for the abdominal aorta and ilium artery.
However, the reliability for the bypassing operation is not always sufficient for the thigh artery and those arteries on the peripheral side from the thigh artery, in the cases of early obliteration that the reconstructed artery is occluded as early as within about 48 hours after the surgical operation, or cases of later obliteration that the reconstructed artery is occluded within about 6 months to 3 years after the surgical operation.
By the way, a relationship between the cases of causing the early occlusion and the cases liable to cause the later occlusion and the blood flow rate waveform (change of the blood flow rate with time) after the surgical operation in the vicinity of the reconstructed artery has been shown recently.
That is, it has been made clear that among five blood flow waveforms O, I, II, III and IV shown in FIGS. 1(a), (b), (c), (d) and (e) (in each of the graphs, the abscissa corresponds to the time t and the ordinate corresponds to the blood flow rate S measured by utilizing the Doppler effect or electromagnetic flow-meter etc.), the waveforms III and IV shown in FIGS. 1(d), (e) have a concern with the cases causing early occlusion, while the waveform II shown in FIG. 1(c) has a concern with the cases causing prognostic occlusion and the waveforms O, I shown in FIGS. 1(a), (b) correspond to the cases causing relatively less prognostic occlusion.
Accordingly, the early occlusion, which is known to be caused by the presence of the occlusion at the sutured site or of the unexpected pathogenic occlusion, can be coped with by instantly searching the cause for the pathogenic change and applying repairement or reconstruction if the blood flow after the operation near the reconstructed artery takes the waveform of III or IV.
However, in the case of the later occlusion for which it has been statistically confirmed that about one-half of the cases showing the blood flow waveform of type II shown, for example, in FIG. 1(c) correspond to the later occlusion but the cause for which has not yet been clarified, no appropriate preventive measures have been established.